[Dovecot] Performance-Tuning

[Javier de Miguel Rodríguez]

     We are very happy with mdbox+zlib+ext4 + iSCSI SAN (HP Lefthand in 
our setup)

     If you have CPU to spare, consider using zlib with mdbox. You are 
trading CPU power (cheap) to get fewer IOPS (IOPS count is expensive). 
Mdbox has halved our backup windows (2,8 TB uncompressed mailboxes, 2 TB 
compressed) and backup software is happier because there are few 
(100.000+ files with mdbox) to backup instead of several millions (Maildir)

     Regards

     Javier
> Hi,
>
> I have>  11 TB hard used Mailstorage, saved als maildir in ext3 on HP EVA.
>
> I always wanted to make some mesurements about several influences to the
> performance (switch to ext4, switch to mdbox), but I never had enough time
> to do that.
>
> At the moment I *need* more speed, we have too much waitI/O on the system
> and I already used all other performance and tuning-tricks (separated cache,
> noatime, fsync and all that stuff).
>
> I have to change my setup, maybe somebody else here have hard facts:
>
> *) Is ext4 faster? How much faster?
> *) Is it faster because of the ext4 kernel-module (which can be used on ext3
> to) or because of the ext4 filesystem layout?
>
>
> *) Is mdbox really faster? I'd like to have mdbox to have better performance
> in running my backup-processes. But does it bring some performance boosts
> to?
>
>
> Thanks for any hints an tricks,
>
> Peer
>
>